Electric motor follow-up system



potential difference, after amplilcation if necessary, is

Z,'7l3,656 rectiiiee and applied to the condenser circuit, preferabl W i i through iii ini ed nce t .i foin r OLai caencrnic if oros rainbow-ni svsrnra P a im tief fo* m 1C@ a @le tronic valve connected as a cathode follower, in order to Stgngy Gea avoid disturbance of conditions in the preceding circuits li/'eadows, i't'ornclnireh, and Robert Norman SiaxoJ, Liverpool, E asslgv -rs o Southern by the comparatively large currents of the condenser United "leiepl'ione Cables Limited, Engenharia Doch, Circuit,

V.-Y`,Ti'l' .n l. iifmfiii: i i iiiis @mimy the invention will be further described with retei'ence Applm April 29 19539 Serial Nd 346,36 l to a particular example. iliustrated by tire accompanying l!) circuit diagram. In this example the circuit to be baliiiiii liii'liy, ilffiliwii Giei iiiiiiii Emi 3i 1952 anced is a bridge A used for testing capacities, for inf .l f i i 1 o 3 Qldlmd (Cl. :lm Zg) `stance the carpacny between the quads oi .communica tion cable. the output troni the bridge A is [ed to an l amplifier S and the output from the amplifier is fed to This invention relates to the automatic obtaining or l5 a balance Control Cfcult D which is Suscepble to the balance in an electric circuit, which, tor instance, may Condition of the bridge i 'wr "a .fi' be a circuit oL the bridge type, b/ tiie adjustment vof the The budge A Comprlses two muuctwe arms N N value of some circuit value representen by a circuit ele- Connected between points 5, 8, and 5, 7 respectively. It ment, or roup of elements, therein. in such an arrangenient the condition of balance is determined by the state of 21 brIlCil (ihf detector bflnh) of ih? Circuit for m` obtained from a pick-up coil L inductively coupled to the stance the diagonal of a bridge, in which the current lhduclors N, N and feedhlg the ampllher B over leadS becomes zero when balance is obtained. We use, in 3 2d. The unknown cadlclty X lo he lesled ls cdd conjunction with such a branch a sensitive polarised heed lh he um d 7 anda Sldhdard Capaclly S ls col-1 relay arranged to be influenced by the ow of current g5 healed ln the other Capaci-Ve arm 6 Ah A C po, in that bHCh, 0T by the PGemi-li diffeen Prsducng tential f is applied to the bridge across the points Siend that ow. in this relay is a centre contact movable be- The hrldge ls balanced h, means of an ddjuslable tween two side contacts and making contact with one emment W Compu-Sing a dhcnhal Condenser wld, one or wtih the other in accord with the direction of ow of hxed late lll cohheced lo the pdlm 3 the other hxed current iii its exciting coil. When balance is obtained plate in cohhecled lo point 7 md the movable plate 9 the movable contact occupies the centre position in which Ohnecled lo the polht d. YlhlS adjustable element thus both Sides Of iiS CifCJii DI@ @Peed- We also 6550105 a provides two adjustable capacities one in parallel with reversible motor device which produces the adjustment the Standard S and the other lh parallel with the lll-1 of the CirCJi eiemeiii 0f elements CCnmed ihis de known X. When rthe bridve is balanced the setting of the Vice being arranged i0 be brought i0 resi Whn balans@ 35 differential condenser W provides a measure of the dif- S Obtained l ference between the capacities of the standard S and The arrangement ofthe apparatus is such that balance unknown X The m0Vglhle dal@ 9 ls drh/6h lhmuoh a of the circuit is always approached and obtained when Shaft n hy means of an dlacmmmelcally acmted the mOtOl' GVC@ iS mOViiig in one Pfi'dermmC11 Sense reversible clutch 33 from a continuoucsly running motor after having moved in the Opposite S628@ This Piece@ 10 er. on the shea i2 are exea two friction dises i6 and ing opposite movement has the eect of preparing part 17. on the mmol. Spindle 2d extending between the of the SOpPiHg CilCUii which becomes effective after the discs 16 and 17 and transversely to the axis of the shaft reversal 0f mOVemGU- i2, and between the discs i6 and l?, is tixed a friction At will be seen that in this procedure the adjustment driving disc lg. Ah exlensloh of lh@ splndle 2d ls en of the circuit element, or elements, is taking place in the gaged by hlmllslhg Springs 9 Whlch normally hold sense awlly from balance at m@ Preliminary Part of it in the position of non-envavernent between the drivini7 the procedure and is then reversed to go towards and disc 18 and lhe Other dlqcal; and 7 The And of th; bring about the conditions for balance. lf oychance the Spindle 2@ "Carries an gnature 2f phe sohdle 2l) ls initial movement when theapparatus comes into opera- Suhclemly flexible to hermit the driving dfsg 18 to be no. 1S towards balance it 1S made to commu@ .pas .the 50 brought into engagement with either ofthe discs lo and point of balance and inove away therefrom 1n older i7 b, ener I-SD om or lha th f l, t h ,i that the required sequence of events may take place. MI y ,i g g f i u 2- 1 Bi C dci magnets and ivil disposed one each side oi vthe spindle 2li) to It is preferred to arrange the control circuit of the www the Mmmm: f7 if th@ q l* VT polarised relay in such a way that the sense of movement Lhlwl r a f" A l im 10p la Lemon' of the relay is determined by the condition whether inl e e ectronanets LA and MJ me permanently com points 8, 6, and 7, 6 respectively. The bridge output is crease or decrease of potential difference in the detector gecd tol FLD C'jqiply G an? alf Sepamly energlsed branch ofthe circuit is taking place. That is, it depends yom? 351g a umm tofu@ l ihmigh acommoll not on the potential difference itself but on whether its s wltch Nil mld [V/oww Swich provlfhng 'LVO P051' rale of Change ls pdslllve or hegalvd This effect can tions BBa and PB J. inthe drawing the circuit is shown be obtained by connecting the coil of the sensitive relay m me. unenefgl'se Confini@ m 'f/hh MK2 i3 Pil and lh Selles Whh a condenser lh the charging and discharg BB3 1s closed in the circuit to tiie anticlockwise maging circuit thereof and applying to that circuit the po- Het MJ' tential difference in the detector branch or some derived l It l? feliled i0 iQCi iii@ B1G/abi@ Pole-i6 0f the difpotential difference. When this potential difference .is infenlai Condenser W When iii@ POSIOH 0f billCe iS creasing the condenser is being charged and the current aifliiled- FOI iiiiS piii'POS 'i'iel'@ iS iiXd 10 the Shaft through the relay is, therefore, iiowing in the charging i2 a IiOiCiled CiiSC i5 and 21 Spring i5 Hofman? maindirection. On the other hand, when the potential diffaiHS a PVOed locking iCh il iOCiiHg engagement ference is falling, the condenser is being discharged and with the disc. The latch l# is drawn out of the locking the current is owing through the relay in the reverse position 'oy an electromagnet M when this is energiscd direction. by closing a switch MKl controlled by arrangements For use with an alternating current circuit, for which to be described hereinafter. The switch MKll is closed1 the apparatus is primarily intended, the outofbalance while the adjustment of the bridge is taking place.

adjustable to obtain a balanced condition and a circuit a current derived from said potential difference, a reversibranch across which the potential difference becomes zero ble drive for said adjustable element and a control cirat balance, the arrangement of a polarised relay having a cuit with means for initiating said drive always in the centre zero open position and two side contact-making same pre-determined sense, means actuated by said relay positions, a condenser and means for applying to said :3 in a rst contact-closing position for reversing the drive condenser a potential diierence derived from the potenfrom that sense, a stopping circuit, and means actuated tial difference across said branch circuit, an operating coil by the relay in the second Contact closed position to prefor said relay in series with said condenser, a reversible pare said stopping circuit, an over-riding holding circuit driving means operating on said adjustable circuit elefor said control circuit and means actuating by said stopment and a control circuit with means for initiating the lu ping circuit for applying said over-riding holding circuit movement of said driving means always in the same to said control circuit when the relay moves to the second sense, said control circuit including said relay contacts, contact closing position, and the said stopping circuit means for reversing the sense of said drive at the making being operative to release said over-riding holding cirof one of the side contacts of said relay and thereby to cuit to bring the drive to rest when the relay moves from cause the making of the second of said side contacts and lo the second contact closed position into the centre zero means prepared for stopping said drive by the closing of position. said second side contacts, said last means being operative to stop the drive at the breaking of contact at the Refeleces Cie U the le 0f this Patent second of the side contacts of said relay. UNTED STATES PATENTS July 19, 1955 P. M. G. TOULON VARIABLE SPEED MOTORS CONTROLLED BY ELECTRONIC TUBES Filed 0G13. 4, 1950 5 Sheets-Sheet l 

